US5150153A - Lithographic device with a suspended object table - Google Patents

Abstract

A lithographic device with a lithographic irradiation system (1, 13) which is fastened near a lower side to a mounting member (5) of a frame (7). The device is provided with a unit (65) which is formed by a positioning device (37), with which an object table (21) arranged below the irradiation system (1, 13) is displaceable, and by a support member (35), over which the object table (21) is guided by means of an aerostatic foot (31). In an operational position, the unit (65) is coupled to a carrier (67) by means of coupling members (73), the carrier (67) being suspended from the mounting member (5) by means of suspension elements (79, 81, 83), so that the unit (65) is arranged between lower frame supports (25) of the frame (7) and a compact construction is obtained.

The unit (65) can be rotated from the operational position to an end position, in which the unit (65) is entirely outside the frame (7) and is easily accessible for maintenance, by means of a rotation mechanism (87) and a swivel mechanism (89).

The lithographic device can be used inter alia for irradiating semiconductor substrates, a semiconductor pattern provided on a mask (11) being imaged on a semiconductor substrate (19) provided on the object table (21) by means of the irradiation system (1, 13).

Description

BACKGROUND OF THE INVENTION

The invention relates to a lithographic device comprising a lithographic irradiation system which has a vertical main axis parallel to a z-direction and is fastened near a lower side to a mounting member belonging to a frame of the device, and comprising a positioning device which is arranged below the irradiation system and by means of which an object table is displaceable relative to the irradiation system over a guide surface of a support member coupled to the positioning device, which guide surface extends perpendicular to the z-direction.

A lithographic device of the kind described in the opening paragraph is used for carrying out a lithographic process on a substrate positioned on the object table, such as, for example, an optical lithographic process in which the irradiation system is provided with a lens system and a light source (for example, a UV-light source), an X-ray lithographic process in which the irradiation system is provided with an X-ray source, or an electrolithographic process in which the irradiation system is provided with an electron tube. U.S. Pat. No. 4,737,823 discloses an optical lithographic device of the kind mentioned in the opening paragraph in which the irradiation system is provided with a lens system which is fastened to the mounting member near a lower side. In this known lithographic device, the support member is a rectangular granite slab which forms part of the frame of the device. Four columns of the frame extending parallel to the z-direction are fastened on the guide surface formed by an upper side of the support member, to which columns the mounting member, which is constructed as a plate extending in a direction transverse to the main axis, with the lens system is fastened at some distance above the support member. At a lower side, the support member is provided with lower frame supports, each provided with a spring member and a damping member.

A frame construction as described above results in a comparatively great constructional height of the device in the z-direction. The constructional height of the known lithographic device is determined inter alia by the height of the lens system, the height of the positioning device and the support member, and the height of the lower frame supports. Such a constructional height is disadvantageous, especially in an application of the device in a conditioned production room for, for example, integrated circuits.

SUMMARY OF THE INVENTION

It is an object of the invention to provide a lithographic device of which the constructional height is comparatively small.

The invention is for that purpose characterized in that the positioning device and the support member are positioned as a unit on a carrier which is suspended from the mounting member. The use of a carrier suspended from the mounting member renders a construction of the frame possible in which the mounting member is fastened on the lower frame supports and in which the positioning device and the support member are arranged between the lower frame supports, so that a compact construction is obtained seen in the z-direction.

It is noted that Japanese Patent Application 61-41426 discloses an optical lithographic device with a suspended object table. The object table in that case, however, is displaceable together with the suspension construction relative to the lens system.

A special embodiment of the lithographic device according to the invention is characterized in that the support member is coupled to the carrier by means of a first elastic coupling member and a first damping member, while the positioning device is fastened to the support member by means of a second elastic coupling member and a second damping member. The use of the said coupling members and damping members and an optimization of the mass of the support member in relation to the mass of the positioning device and the mass of the frame provides an optimized mechanical screening of the positioning device from external vibrations such as, for example, mechanical resonance vibrations of the frame of the device.

A further embodiment of the lithographic device according to the invention, which provides a particularly rigid and light suspension of the carrier from the mounting member seen in the direction of the main axis, is characterized in that the carrier of the support member and of the positioning device is suspended from the mounting member by means of plate-shaped suspension elements, each of the said suspension elements extending in a vertical plane which is parallel to the main axis.

A still further embodiment of the lithographic device according to the invention, which provides a particularly rigid, light and compact suspension of the carrier from the mounting member seen in a direction transverse to the main axis and a compact construction of the frame, is characterized in that the carrier is suspended from the mounting member by means of three plate-shaped suspension elements, the mounting member being fastened on a base of the frame by means of three lower frame supports, while the suspension elements are arranged in a triangle and the said vertical planes enclose mutual angles of substantially 60°, each of the lower frame supports being positioned near an external side of one of the suspension elements seen in a radial direction relative to the main axis.

A special embodiment of the lithographic device according to the invention is characterized in that the unit formed by the support member and the positioning device is displaceable in a direction transverse to the main axis relative to the carrier and the mounting member. The positioning device with the object table is readily accessible to an operator of the lithographic device for, for example, maintainance or repairs, in that the said unit is displaced relative to the carrier and the mounting member.

A further embodiment of the lithographic device according to the invention, in which the said unit is displaceable by means of a simple construction, is characterized in that the unit formed by the support member and the positioning device is rotatable relative to the carrier and the mounting member about an axis of rotation which is directed substantially parallel to the main axis.

A yet further embodiment of the lithographic device according to the invention is characterized in that the unit is rotatable by a first rotation movement from an operational position, in which the support member is coupled to the carrier, to a first intermediate position, is rotatable by a second rotation movement from the first intermediate position to a second intermediate position, and is rotatable by a third rotation movement from the second intermediate position to an end position in which the unit is entirely outside the frame. Since the unit is rotatable relative to the frame by the three said rotation movements, the unit can be brought outside the frame in a practical and effective way, particularly when the frame is provided with lower frame supports and suspension elements positioned in a triangle. The positioning device is thereby accessible for minor cleaning operations in the second intermediate position of the unit, while the unit is readily accessible for repairs in the said end position.

A special embodiment of the lithographic device according to the invention, in which the unit is rotatable relative to the carrier substantially without friction, is characterized in that during the first rotation movement of the unit the support member is coupled to a rotation shaft connected to the frame and is guided over an upper surface of the carrier by means of a static fluid bearing.

A further embodiment of the lithographic device according to the invention is characterized in that in the first intermediate position of the unit the support member is couplable to a second rotation arm which is rotatably supported on a first rotation arm rotatably mounted to the frame, the second rotation arm being locked relative to the first rotation arm and the first rotation arm being locked relative to the frame during the first rotation movement of the unit, in that the second rotation movement of the unit is formed by a rotation movement of the second rotation arm relative to the first rotation arm, during which the support member is coupled to the second rotation arm and the first rotation arm is locked relative to the frame, in that the second rotation arm can be locked relative to the first rotation arm in the second intermediate position of the unit, and in that the third rotation movement of the unit is formed by a rotation movement of the first rotation arm relative to the frame, during which the support member is coupled to the second rotation arm and the second rotation arm is locked relative to the first rotation arm. The use of the two rotation arms means that the unit can be rotated to outside the frame by hand in a quick and simple way.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is explained in more detail below with reference to the drawing, in which:

FIG. 1 is a perspective view of an optical lithographic device according to the invention,

FIG. 2 shows a unit constituted by a positioning device and a support member of the optical lithographic device of FIG. 1,

FIG. 3a diagrammatically shows a cross-section of the optical lithographic device of FIG. 1 in which the unit of FIG. 2 is in an operational position,

FIG. 3b diagrammatically shows a cross-section of the optical lithographic device of FIG. 1 in which the unit of FIG. 2 is in a first intermediate position,

FIG. 3c diagrammatically shows a cross-section of the optical lithographic device of FIG. 1 in which the unit of FIG. 2 is in a second intermediate position,

FIG. 3d diagrammatically shows a cross-section of the optical lithographic device of FIG. 1 in which the unit of FIG. 2 is in an end position,

FIG. 4a shows a cross-section of a coupling base of the support member taken on the line IVa--IVa in FIG. 3d,

FIG. 4b shows a cross-section of a pneumatic coupling member of the carrier taken on the line IVb--IVb in FIG. 3d,

FIG. 5a is a plan view of a pneumatic rotation mechanism by which the unit of FIG. 2 is rotatable from the operational position shown in FIG. 3a to the first intermediate position shown in FIG. 3b,

FIG. 5b shows a cross-section of the rotation mechanism taken on the line Vb--Vb in FIG. 5a,

FIG. 5c shows a cross-section of the rotation mechanism taken on the line Vc--Vc in FIG. 5a,

FIG. 6 is a side elevation of a swivel mechanism of the optical lithographic device of FIG. 1,

FIG. 7 is a side elevation of an end of a rotation arm of the swivel mechanism of FIG. 6,

FIG. 8 is a plan view of the swivel mechanism of FIG. 6,

FIG. 9a shows a cross-section of the end of the rotation arm taken on the line IXa--IXa in FIG. 7,

FIG. 9b shows a cross-section of the end of the rotation arm taken on the line IXb--IXb in FIG. 7, and

FIG. 9c shows a cross-section of the end of the rotation arm taken on the line IXc--IXc in FIG. 7.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The optical lithographic device illustrated in FIGS. 1 to 9 is provided with an optical irradiation system 1, shown merely diagrammatically in FIG. 1, which comprises alens system 2 arranged in a vertical z-direction. Thelens system 2 has an opticalmain axis 3 extending in a direction parallel to the z-direction and is provided with a mounting ring 4 near a lower side. By means of the mounting ring 4, thelens system 2 is mounted to a mountingmember 5 which forms part of aframe 7 of the device and which is constructed as a triangular plate extending in a plane perpendicular to the opticalmain axis 3. Near an upper side of thelens system 2, the optical lithographic device is provided with amask manipulator 9 for positioning and supporting amask 11 relative to thelens system 2. During operation, a light beam coming from alight source 13 of the irradiation system 1 is guided viamirrors 15 and 17 of the irradiation system 1 through themask 11 which contains, for example, a pattern of an integrated semiconductor circuit, and focused by thelens system 2 on a substrate such as, for example, asemiconductor substrate 19 provided on an object table 21. In this way the said pattern is imaged on a reduced scale on thesemiconductor substrate 19. The object table 21 is displaceable parallel to an x-direction which is perpendicular to the opticalmain axis 3, and parallel to a y-direction which is perpendicular to the opticalmain axis 3 and to the x-direction. Thesemiconductor substrate 19 can be illuminated in a large number of locations corresponding to identical integrated circuits by means of a stepwise displacement of the object table 21 parallel to the x-direction and the y-direction to different illumination positions. It is noted that the centre of gravity of thelens system 2 is situated near a central plane of the mounting ring 4 extending transverse to the z-direction, so that a stable support of thelens system 2 relative to theframe 7 is provided by the mounting ring 4.

The mountingmember 5 is provided with threecorner portions 23 which each rest on alower frame support 25. Only twocorner portions 23 and two lower frame supports 25 are visible in FIG. 1. The lower frame supports 25 are positioned on abase portion 27 of theframe 7 which is placed on a flat foundation by means ofadjustment members 29. By means of the lower frame supports 25, which are each provided with a spring member and a damping member of a kind known per se and not shown in any detail in FIG. 1, the optical lithographic device is low-frequency (3 Hz) spring-supported on the foundation in a direction parallel to the z-direction and in a direction transverse to the z-direction. In this way it is prevented that vibrations of the foundation, which adversely affect an accurate operation of the optical lithographic device, are transmitted through the lower frame supports 25 to the mountingmember 5 and to thelens system 2.

As is shown in detail in FIG. 2, the object table 21 is guided over anupper surface 33 of asupport member 35 in the form of a granite slab extending perpendicular to the opticalmain axis 3 by means of a so-calledaerostatic foot 31, which is provided with a static gas bearing. The object table 21 is displaceable over theupper surface 33 by means of apositioning device 37 which comprises three linearelectric motors 39, 41 and 43. As is shown in FIG. 2, thelinear motor 39 comprises an x-stator 45 extending parallel to the x-direction and an x-translator 47 fastened to the object table 21 by which the object table 21 is displaceable along the x-stator 45 parallel to the x-direction. Thelinear motors 41 and 43 respectively comprise a y-stator 49 extending parallel to the y-direction with a y-translator 53 fastened to afirst end 51 of the x-stator 45, and a y-stator 55 extending parallel to the y-direction with a y-translator 59 fastened to a second end 57 of the x-stator 45. The y-stators 49 and 55 are fastened to awindow frame 61 of thepositioning device 37, which frame is fastened near its corners on theupper surface 33 of thesupport member 35. As FIG. 2 shows,rubber plates 63 are provided there between theframe 61 and theupper surface 33 of thesupport member 35. The use of therubber plates 63 prevents high-frequency vibrations, such as, for example, natural vibrations of theframe 7, from being transmitted to the object table 21 via thesupport member 35 and theframe 61. The object table 21 is displaceable by means of thelinear motors 41 and 43 parallel to the y-direction and rotatable through a very limited angle about an axis of rotation which is parallel to the opticalmain axis 3. It is noted that theaerostatic foot 31 and thepositioning device 37 with thelinear motors 39, 41 and 43 positioned in an H-arrangement relative to one another are known per se from U.S. Pat. No. 4,737,823.

As is shown in FIGS. 1 and 2, thesupport member 35 and thepositioning device 37 constitute aunit 65 which is provided on acarrier 67 of theframe 7. FIGS. 3a to 3d show that thecarrier 67 is formed by a substantially triangular plate extending perpendicular to the opticalmain axis 3 and havingmajor sides 69 which each extend between two lower frame supports 25. Anupper side 71 of thecarrier 67 is provided with threepneumatic coupling members 73 depicted only diagrammatically in FIGS. 3a to 3d, which in an operational position of theunit 65 shown in FIG. 3a are in engagement with threecoupling bases 77 of thesupport member 35 provided at alower side 75 of thesupport member 35. Thecoupling members 73 of thecarrier 67 and the coupling bases 77 of thesupport member 35 are described in more detail below. Thecarrier 67 is suspended from alower side 85 of the mountingmember 5 indicated in FIG. 1 by means of three plate-shapedsuspension elements 79, 81 and 83. In FIG. 1, only thesuspension elements 79 and 81 are partly visible, while in FIGS. 3a to 3d thesuspension elements 79, 81 and 83 are shown in cross-section. Thesuspension elements 79, 81 and 83 are each formed by a plate which extends in a vertical plane parallel to the opticalmain axis 3, the relevant vertical planes enclosing angles of substantially 60° with one another. The use of thesuspension elements 79, 81 and 83 provides a suspended construction of thecarrier 67 with the mountingmember 5, theunit 65 formed by thesupport member 35 and thepositioning device 37 being arranged between the lower frame supports 25. In this way a compact construction of the optical lithographic device is obtained seen both in the z-direction and transverse to the z-direction. Furthermore, the said suspended construction has a high rigidity in the direction of the opticalmain axis 3 and in a direction perpendicular to the opticalmain axis 3 through the use of thesuspension elements 79, 81 and 83. Moreover, the use of the suspended construction achieves that the centre of gravity of the displaceable parts of thepositioning device 37 is situated near a central plane of the lower frame supports 25 which extends transverse to the z-direction. The spring members and damping members of the lower frame supports 25 referred to earlier are present in the said central plane. This limits undesirable movements of theframe 7 on the lower frame supports 25 caused by reactional forces exerted by the moving parts of thepositioning device 37 on theframe 7 via thesupport member 35.

It is achieved through the compact construction of the optical lithographic device in the z-direction that an admissible constructional height of the device is not exceded. The admissible constructional height is determined by an available height in an operational room for the device, such as, for example, a conditioned production room for integrated circuits. The compact construction of the device also has the result, however, that thepositioning device 37 with the object table 21 in the operational position shown in FIG. 3a is less easily accessible to an operator of the device for, for example, maintainance or repairs. To render thepositioning device 37 better accessible for maintainance, the device is provided with apneumatic rotation mechanism 87 which is fastened to thecarrier 67 and which is shown merely diagrammatically in FIGS. 3a-3d, and with aswivel mechanism 89 which is fastened to thebase portion 27 of theframe 7. By means of thepneumatic rotation mechanism 87, theunit 65 is rotatable relative to thecarrier 67 about arotation pin 91 of thecarrier 67 which is directed parallel to the opticalmain axis 3 from the operational position shown in FIG. 3a to a first intermediate position shown in FIG. 3b. Thepositioning device 37 is accessible for, for example, minor cleaning work in the first intermediate position. Theswivel mechanism 89 is provided with afirst rotation arm 93, which is rotatable relative to theframe 7 about afirst hinge pin 95 of thebase portion 27 directed parallel to the opticalmain axis 3, and with asecond rotation arm 97 which is rotatable relative to thefirst rotation arm 93 about asecond hinge pin 99 of thefirst rotation arm 93 directed parallel to the opticalmain axis 3. By means of theswivel mechanism 89, theunit 65 is rotatable from the first intermediate position depicted in FIG. 3b to a second intermediate position depicted in FIG. 3c by a rotation of thesecond rotation arm 97 relative to thefirst rotation arm 93. Theunit 65 is rotatable from the second intermediate position to an end position depicted in FIG. 3d by a rotation of thefirst rotation arm 93 relative to theframe 7. In the end position shown in FIG. 3d theunit 65 is entirely outside theframe 7, and the positioning device is easily accessible for maintainance or repairs. Thepneumatic rotation mechanism 87 and theswivel mechanism 89 are described in detail below.

As was described above, thesupport member 35 is coupled to thecarrier 67 by means of thepneumatic coupling members 73 and the coupling bases 77 in the operational position depicted in FIG. 3a. As FIGS. 3d and 4a show, eachcoupling base 77 is provided with a C-shapedclamping plate 101 havinglegs 103 which is screwed to a disc-shapedportion 105 of therelevant coupling base 77. Thecoupling base 77 is further provided with a circularcylindrical portion 107 which is glued in ahole 109 drilled in thelower side 75 of thesupport member 35. A first drilledhole 111 and a seconddrilled hole 113 which has a reduced diameter compared with the firstdrilled hole 111 are provided in the circularcylindrical portion 107 of thecoupling base 77. A circularcylindrical end 115 of asupport pin 117, which is present with clearance in the firstdrilled hole 111, is glued in the seconddrilled hole 113. Thesupport pin 117 is further provided with two portions of reduced diameter which each form a so-calledelastic hinge 119, and with asupport face 121. Finally, thecoupling base 77 is provided with a disc-shapedrubber plate 123 which is glued between the disc-shapedportion 105 and the circularcylindrical portion 107.

As is shown in FIGS. 3d and 4b, eachpneumatic coupling member 73 is provided with twolevers 125 which are fastened to arotation pin 127, whichpin 127 is journalled in ablock 129 fastened to thecarrier 67. Eachlever 125 is provided with a clamping element 133 near a first end 131, and is fastened to apiston 137 with sealingring 139, which is displaceable in acylinder 141, near asecond end 135. Furthermore, twoholes 143 are drilled in theupper side 71 of thecarrier 67. A pretensioned mechanicalhelical spring 145, which bears on aspring holder 147 of one of thelevers 125, is provided in each drilledhole 143. Theblock 129 is further provided with three contact faces 149 (see FIG. 3d).

In the operational condition shown in FIG. 3a, thesupport face 121 of eachcoupling base 77 bears on the three contact faces 149 of one of thecoupling members 73. The twolegs 103 of the C-shapedclamping plate 101 are below the two clamping elements 133 of thecoupling member 73 during this. The clamping elements 133 are pressed against thelegs 103 of theclamping plate 101 under spring pressure of the mechanicalhelical springs 145, so that thesupport face 121 of thesupport pin 117 is securely pressed against the three contact faces 149 of theblock 127.

The use of the support pins 117 provides a rigid coupling of theunit 65 to thecarrier 67 seen in the z-direction. In a direction transverse to the z-direction, the support pins 117 are elastically deformable owing to the use of the elastic hinges 119, so that differences in thermal expansion between thesupport member 35 and thecarrier 67 are accommodated by elastic deformation of the support pins 117. The use of the disc-shapedrubber plates 123 prevents high-frequency vibrations, such as, for example, natural vibrations of theframe 7, from being transmitted to thesupport member 35 via thecoupling members 73 and the coupling bases 77. Thepositioning device 37 is mechanically optimally screened against the said natural vibrations of theframe 7 in that therubber plates 123 in combination with therubber plates 63 referred to above are used and in that the mass of thesupport member 35 is optimized in relation to the mass of thepositioning device 37 and the mass of theframe 7.

As was noted above, theunit 65 is rotatable by means of thepneumatic rotation mechanism 87 from the operational position shown in FIG. 3a to the first intermediate position shown in FIG. 3b. Therotation mechanism 87 depicted in FIGS. 5a to 5c is provided with aswitch bar 151 which is rotatable about arotation axle 153 which is parallel to the opticalmain axis 3. Therotation axle 153 is connected to ablock 155 which is fastened on thecarrier 67 and which is provided with arecess 157 which extends transverse to therotation axle 153. Theswitch bar 151 is provided with alongitudinal slot 161 near alower side 159. Therotation mechanism 87 is further provided with apneumatic drive motor 163 which is fastened to alower side 165 of thecarrier 67. Anoutput shaft 167 of thedrive motor 163 which is directed parallel to therotation axle 153 is provided with alateral arm 169 near an end. Aroller member 171 is provided on thelateral arm 169 eccentrically relative to theoutput shaft 167, whichroller member 171 is situated substantially without clearance betweenside walls 173 and 175 of the saidslot 161. When thelateral arm 169 is rotated by thepneumatic drive motor 163, theswitch bar 151 is rotated about therotation axle 153.

As is shown in FIG. 5b, ahole 177 is drilled in theblock 155 and in thecarrier 67, which hole is situated coaxially relative to the saidrotation axle 153. Therotation pin 91 mentioned above is provided in the drilledhole 177, where it can be shifted by means of a first pneumatic short-stroke cylinder 179. As FIGS. 5a and 5c show, acoupling mechanism 181 with ablock 183 is fastened to theswitch bar 151, theblock 183 being provided with arecess 185 which extends transverse to therotation axle 153 and with a drilledhole 187. A lockingpin 189 can be shifted in the drilledhole 187 by means of a second pneumatic short-stroke cylinder 191. Acoupling plate 193 shown in FIGS. 3a to 3d which is fastened to thelower side 75 of thesupport member 35 and which is provided with a firstdrilled hole 195 and a seconddrilled hole 197 is situated in the said recesses 157 and 185 in the operational position depicted in FIG. 3a. The firstdrilled hole 195, which has a diameter equal to the diameter of the drilledhole 177, is thereby coaxial with the drilledhole 177, and the seconddrilled hole 197, which has a diameter equal to the diameter of the drilledhole 187, is coaxial with the drilled hole 187 (see FIGS. 5b and 5c).

To turn theunit 65 from the operational position to the first intermediate position, therotation pin 91 and thelocking pin 189 are passed into the firstdrilled hole 195 and the seconddrilled hole 197 by means of the first short-stroke cylinder 179 and the second short-stroke cylinder 191, respectively, so that theunit 65 is coupled to theswitch bar 151 through thecoupling plate 193. Then theunit 65 is uncoupled from thecarrier 67 through the supply of compressed air to thecylinders 141 of thecoupling members 73. Simultaneously threestatic gas bearings 199 fastened to thelower side 75 of thesupport member 35 are put into operation, after which theunit 65 is rotated about therotation pin 91 by means of therotation mechanism 87. Theunit 65 is guided over theupper side 71 of thecarrier 67 substantially without friction thanks to the use of thestatic gas bearings 199 during this.

As is diagrammatically shown in FIGS. 3a to 3d, acoupling mechanism 201 is fastened to theupper side 71 of thecarrier 67. Thecoupling mechanism 201 is of a similar kind to thecoupling mechanism 181 of theswitch bar 151 and is not shown in any further detail in FIGS. 3a to 3d. Afurther coupling plate 203 with a drilledhole 205 is also fastened to thelower side 75 of thesupport member 35. After theunit 65 has been returned from the first intermediate position to the operational position, theunit 65 is brought into an accurate position relative to thecarrier 67 by means of thecoupling mechanism 201 in that a locking pin (not shown in the Figures) of thecoupling mechanism 201 is passed into the drilledhole 205 of thecoupling plate 203. After that, thestatic gas bearings 199 are switched off and theunit 65 is coupled to thecarrier 67 by means of thecoupling members 73 through the discharge of the compressed air from thecylinders 141. Finally, thecoupling plate 203 is disengaged from thecoupling mechanism 201 and therotation pin 91 and thelocking pin 189 are removed from the firstdrilled hole 195 and the seconddrilled hole 197 of thecoupling plate 193 by the first short-stroke cylinder 179 and the second short-stroke cylinder 191, respectively.

In the first intermediate position depicted in FIG. 3b, thesupport member 35 rests with thelower side 75 on asupport plate 207 of thesecond rotation arm 97 of theswivel mechanism 89. Thesupport plate 207 extends alongside thesecond rotation arm 97 and is situated in a plane transverse to the opticalmain axis 3. Thesupport member 35 further rests on asupport wheel 209 in the first intermediate position, which support wheel is rotatably fastened to anend 211 of thefirst rotation arm 93 of theswivel mechanism 89. To support thesupport member 35 in the first intermediate position, furthermore, thestatic gas bearings 199 are operational.

As is shown in FIG. 8, arecess 213 is provided in thesupport plate 207. In the first intermediate position, a lockingpawl 215 fastened to thelower side 75 of thesupport member 35 and shown in FIGS. 3a to 3d is situated in therecess 213. Thesecond rotation arm 97 is provided with alocking mechanism 217 with ahook 219 which is drawn around the lockingpawl 215 by means of apneumatic cylinder 221 in the first intermediate position. Theunit 65 is thus coupled to thesecond rotation arm 97 of theswivel mechanism 89. Theunit 65 is uncoupled from therotation mechanism 87 after that in that therotation pin 91 and thelocking pin 189 are removed from the first and the seconddrilled hole 195, 197 of thecoupling plate 193 by means of the first and the second short-stroke cylinder 179, 191, respectively.

As FIGS. 6, 7 and 8 show, thefirst rotation arm 93 is provided with afirst hinge housing 223 having a drilledhole 225. Thefirst rotation arm 93 can rotate about thefirst hinge pin 95 referred to above and fastened to thebase portion 27 by means of thefirst hinge housing 223. Thesecond rotation arm 97 is provided with asecond hinge housing 227 having a drilledhole 229. Thesecond rotation arm 97 can rotate about thesecond hinge pin 99 fastened to twohorizontal plates 230 of thefirst hinge housing 223 by means of thesecond hinge housing 227. Thefirst rotation arm 93 is further provided with aslide arm 231 withslots 233. Theslide arm 231 can slide alongbolts 235 which are screwed through theslots 233 into thefirst rotation arm 93. Theslide arm 231 is provided with a coupling pin 239 near a first end 237. The coupling pin 239 is in engagement with arecess 241 of acoupling plate 243 which is fastened to thesecond hinge housing 227. The assembly of the coupling pin 239 and thecoupling plate 243 ensures that theslide arm 231 is shifted along thebolts 235 when thesecond rotation arm 97 is rotated about thesecond hinge pin 99.

As is shown in detail in FIGS. 7 and 9a, theslide arm 231 is provided with afirst recess 247 near asecond end 245. Furthermore, a tiltinglever 249 withhandle 251 is fastened to theend 211 of thefirst rotation arm 93. The tiltinglever 249 is rotatable about abolt 253 which is screwed into theend 211 of thefirst rotation arm 93 and which is provided with a lockingpawl 255. In the first intermediate position of theunit 65, theslide arm 231 is in a position as shown in FIG. 7, whereby the lockingpawl 255 of the tiltinglever 249 is held in thefirst recess 247 of theslide arm 231 by means of amechanical spring 257. In this way thesecond rotation arm 97 is locked relative to thefirst rotation arm 93 in the operational position, during rotation of theunit 65 from the operational position to the first intermediate position, and in the first intermediate position.

As is shown in detail in FIGS. 7 and 9b, theend 211 of thefirst rotation arm 93 is provided with alocking bolt 259 which can rotate in a drilledhole 261 provided in theend 211. As FIG. 9b shows, the lockingbolt 259 is provided with a C-shapedend 263 having a circularouter wall 265 which is guided along a circularinner wall 267 of the drilledhole 261, and having a circularinner wall 269 which is provided eccentrically relative to theouter wall 265. In the first intermediate position of theunit 65, the C-shapedend 263 of thelocking bolt 259 is in engagement with a lockingpawl 271 which is fastened to thebase portion 27 of theframe 7 and which is shown diagrammatically in FIG. 9b. Rotation of thelocking bolt 259 is prevented during this by a fixedlocking pin 273 which is fastened to theend 211 of thefirst rotation arm 93 and by alocking block 275 which is fastened to thesecond end 245 of theslide arm 231 and which is in a position as shown in FIG. 7 in the first intermediate position of theunit 65. In this way thefirst rotation arm 93 is locked relative to theframe 7 in the operational position, during rotation of theunit 65 from the operational position to the first intermediate position, and in the first intermediate position.

To turn theunit 65 from the first intermediate position to the second intermediate position, the tiltinglever 249 is rotated by hand about thebolt 253 against the spring pressure of themechanical spring 257, so that the lockingpawl 255 of the tiltinglever 249 is released from thefirst recess 247 of theslide arm 231 and thesecond rotation arm 97 is unlocked relative to thefirst rotation arm 93. Thesecond rotation arm 97 is then turned by hand about thesecond hinge pin 99, during which thelower side 75 of thesupport member 35 is guided over thesupport wheel 209. During rotation of theunit 65 from the first intermediate position to the second intermediate position, thestatic gas bearings 199 remain operational, so that a stable support is provided for theunit 65. When the second intermediate position is reached, theslide arm 231 is shifted so far that the lockingpawl 255 of the tiltinglever 249 is pulled into asecond recess 277 of theslide arm 231 under the influence of themechanical spring 257. Thus thesecond rotation arm 97 is locked relative to thefirst rotation arm 93 in the second intermediate position. In this second intermediate position, thestatic gas bearings 199 are switched off since theunit 65 is supported in a stable manner in this intermediate position by thesupport plate 207 of thesecond rotation arm 97 and by thesupport wheel 209 of thefirst rotation arm 93. When thestatic gas bearings 199 are switched off, asafety pawl 279 shown in FIGS. 7 and 9c is automatically slid into arecess 283 of the tiltinglever 249 by means of a further pneumatic short-stroke cylinder 281 fastened to theend 211 of thefirst rotation arm 93. The use of thesafety pawl 279 prevents the lockingpawl 255 of the tiltinglever 249 from being removed from thesecond recess 279 and prevents theunit 65 from being returned to the first intermediate position when thestatic gas bearings 199 are not operating.

In the second intermediate position of theunit 65 shown in FIG. 3c, theslide arm 231 is shifted so far that thelocking block 275 of theslide arm 231 shown in FIGS. 7 and 9b just clears the C-shapedend 263 of thelocking bolt 259 and thelocking bolt 259 is rotatable. When thelocking bolt 259 is rotated through an angle of substantially 180° the lockingpawl 271 fastened to thebase portion 27 is released and thefirst rotation arm 93 is unlocked relative to theframe 7. Thefirst rotation arm 93 is now rotatable by hand about thefirst hinge pin 95 from the second intermediate position to the end position shown in FIG. 3d.

As is shown in FIGS. 7 and 9c, asafety lever 285 is provided near theend 211 of thefirst rotation arm 93, which safety lever is rotatable about arotation pin 287 and is provided with astop 289. A furthermechanical spring 295 is provided with pre-tension in arecess 291 of thesafety lever 285 and arecess 293 of theend 211 of thefirst rotation arm 93. When thefirst rotation arm 93 is locked relative to thebase portion 27 in the second intermediate position of theunit 65, thesafety lever 285 is held in a position shown in FIG. 9c against the spring pressure of themechanical spring 295 since thestop 289 of thesafety lever 285 bears on thebase portion 27. The tiltinglever 249 is rotatable in this position of thesafety lever 285. When thefirst rotation arm 93 has been turned away from thebase portion 27, thesafety lever 285 is turned to against theshaft portion 297 of thelocking bolt 259, which portion has a reduced diameter compared with the drilledhole 261, under the influence of themechanical spring 295. In this position of thesafety lever 285, the tiltinglever 249 when rotated is checked by thesafety lever 285, so that thesecond rotation arm 97 cannot be unlocked relative to the first lever.

It is noted that, instead of the plate-shapedcarrier 67, alternative carriers may be used, such as, for example, a frame carrier. It is also possible to use, instead of thecarrier 67, a construction in which thesupport member 35 is provided with a number of fastening members by which thesupport member 35 is fastened to thesuspension elements 79, 81, 83. The use of a plate-shapedcarrier 67, however, provides a number of constructional advantages such as, for example, the use of therotation mechanism 87 with thestatic gas bearings 199.

It is further noted that, instead of the plate-shapedsuspension elements 79, 81, 83, alternative suspension elements, such as, for example, rod-shaped suspension elements, or a different number of suspension elements, may be used. The use of the three plate-shapedsuspension elements 79, 81, 83, however, as described above, provides a particularly rigid and compact suspension of thecarrier 67 from thelower side 85 of the mountingmember 5. It is further noted that thecarrier 67 may also be suspended from an upper side of the mountingmember 5, for example, by means of a brace or a bracket construction. It is essential in this connection, however, that thecarrier 67 with theunit 65 should be positioned between the lower frame supports 25, so that a particularly compact construction of the optical lithographic device in the z-direction is obtained.

It is further noted that the use of therubber plates 63 between thepositioning device 37 and thesupport member 35 and of therubber plates 123 between thesupport member 35 and thecarrier 67 achieves in a constructionally particularly simple manner that thepositioning device 37 is screened from mechanical vibrations of the frame7. Instead of therubber plates 63 and therubber plates 123, alternative spring members or combinations of a spring member and a damping member may also be used, so that a greater bandwidth may be achieved. In general, however, this leads to a more intricate construction of the saidunit 65.

It is further noted that, especially in the case of a compact construction of theframe 7 with lower frame supports 25 andsuspension elements 79, 81, 83 arranged in a triangle, a displacement of theunit 65 to outside theframe 7 is rendered possible by the use of therotation mechanism 87 in conjunction with theswivel mechanism 89, theunit 65 being rotatable by three consecutive rotation movements from the operational position to the end position. A displacement mechanism by means of which only the positioning device or a unit formed by the positioning device and the support member can be moved relative to the frame can be applied also in other lithographic devices, in which the frame has a less compact construction or more than three lower frame supports 25, or in which the support member forms a base part of the frame. It is also possible then to use a translation movement of the positioning device or of the unit instead of one or several rotation movements. When a translation movement is used, the displacement mechanism may be provided, for example, with one or several straight guide rails, the support member being fitted with roller members.

It is further noted that instead of the rotation mechanism 87 a rotation mechanism of simpler construction may be used, theunit 65 being manually turned from the operational position to the first intermediate position. The use of therotation mechanism 87, however, whereby theunit 65 is rotated by means of adrive motor 163, and of thecoupling mechanism 201 renders a more accurate positioning of theunit 65 in the operational position possible.

Finally, it is noted that the optical lithographic device described above is eminently suitable for illuminating semiconductor substrates in the manufacture of integrated electronic circuits. Such a lithographic device, however, is also applicable in the manufacture of other products having structures with detail dimensions in the micron or submicron range, where mask patterns have to be imaged on a substrate by means of the device. Possibilities here are structures of integrated optical systems, or conductor and detection patterns of magnetic domain memories, and structures of liquid crystal imaging patterns.

Claims (9)

We claim:

1. A lithographic device comprising a lithograpic irradiation system which has a vertical main axis parallel to a z-direction and is fastened near a lower side to a mounting member belonging to a frame of the device, and comprising a positioning device which is arranged below the irradiation system and by means of which an object table is displaceable relative to the irradiation system over a guide surface of a support member coupled to the positioning device, which guide surface extends perpendicular to the z-direction, characterized in that the positioning device and the support member are positioned as a unit on a carrier which is suspended from the mounting member.

2. A lithographic device as claimed in claim 1, characterized in that the support member is coupled to the carrier by means of a first elastic coupling member and a first damping member, while the positioning device is fastened to the support member by means of a second elastic coupling member and a second damping member.

3. A lithographic device as claimed in claim 1 or 2, characterized in that the carrier of the support member and of the positioning device is suspended from the mounting member by means of plate-shaped suspension elements, each of the said suspension elements extending in a vertical plane which is parallel to the main axis.

4. A lithographic device as claimed in claim 3, characterized in that the carrier is suspended from the mounting member by means of three plate-shaped suspension elements, the mounting member being fastened on a base of the frame by means of three lower frame supports, while the suspension elements are arranged in a triangle and the said vertical planes enclose mutual angles of substantially 60°, each of the lower frame supports being positioned near an external side of one of the suspension elements seen in a radial direction relative to the main axis.

5. A lithographic device as claimed in any one of the preceding claims, characterized in that the unit formed by the support member and the positioning device is displaceable in a direction transverse to the main axis relative to the carrier and the mounting member.

6. A lithographic device as claimed in any one of the preceding claims, characterized in that the unit formed by the support member and the positioning device is rotatable relative to the carrier and the mounting member about an axis of rotation which is directed substantially parallel to the main axis.

7. A lithographic device as claimed in claim 6, characterized in that the unit is rotatable by a first rotation movement from an operational position, in which the support member is coupled to the carrier, to a first intermediate position, is rotatable by a second rotation movement from the first intermediate position to a second intermediate position, and is rotatable by a third rotation movement from the second intermediate position to an end position in which the unit is entirely outside the frame.

8. A lithographic device as claimed in claim 7, characterized in that during the first rotation movement of the unit the support member is coupled to a rotation shaft connected to the frame and is guided over an upper surface of the carrier by means of a static fluid bearing.

9. A lithographic device as claimed in claim 7 or 8, characterized in that in the first intermediate position of the unit the support member is couplable to a second rotation arm which is rotatably supported on a first rotation arm rotatably mounted to the frame, the second rotation arm being locked relative to the first rotation arm and the first rotation arm being locked relative to the frame during the first rotation movement of the unit, in that the second rotation movement of the unit is formed by a rotation movement of the second rotation arm relative to the first rotation arm, during which the support member is coupled to the second rotation and the first rotation arm is locked relative to the frame, in that the second rotation arm can be locked relative to the first rotation arm in the second intermediate position of the unit, and in that the third rotation movement of the unit is formed by a rotation movement of the first rotation arm relative to the frame, during which the support member is coupled to the second rotation arm and the second rotation arm is locked relative to the first rotation arm.

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